Over the last millennium patterns of mortality have changed and have determined who grieves and how. At all times grief has been recognised as a threat to physical and mental health. More recently the scientific study of bereavement has enabled us to quantify such effects and to develop theoretical explanations for them. This paper reviews our evolving understanding of grief, focusing especially on the developments in research, theory and practice that have taken place during the twentieth century. Wars and similar conflicts are associated with repression of grief but methods of helping by facilitating its expression, which were introduced during the two World Wars are less needed and effective at other times. In recent years more attention has been paid to the social context in which grief arises and, particularly, to the nature of the attachments which precede and influence the reaction to bereavement and to other traumatic life events. At the same time a range of caring resources have become available and acceptable to bereaved people and the results of scientific evaluation of these give promise that we are moving towards an era in which more sensitive and appropriate care will be provided to the bereaved by both voluntary and professional caregivers.